Circuit interrupting device having printed circuit board coils

ABSTRACT

A circuit interrupter including a line conductor, a neutral conductor, a printed-circuit board coil, and a test circuit. The printed-circuit board coil has an aperture configured to receive the line conductor. The test circuit is electrically connected to the printed-circuit board coil. The test circuit is configured to determine an arc fault condition based on a signal of the printed-circuit board coil.

RELATED APPLICATIONS

This application claims priority to U.S. Provisional Patent ApplicationNo. 62/703,106, filed on Jul. 25, 2018, the entire contents of which areincorporated herein by reference.

FIELD

Embodiments relate to circuit interrupting devices, such as a groundfault circuit interrupter (GFCI) and/or an arc fault circuit interrupter(AFCI).

SUMMARY

Circuit interrupters are safety devices intended to protect a user fromelectric shock. GFCIs sense an imbalance in current flowing between hotand neutral conductors, and cut off power to the load, while AFCI sensean arc fault, and cut off power to the load. GFCI and/or AFCI may beimplemented into electrical receptacles. In such an implementation,space within the electrical receptacle may be an issue.

Thus, one embodiment provides a circuit interrupter including a lineconductor, a neutral conductor, a printed-circuit board coil, and a testcircuit. The printed-circuit board coil has an aperture configured toreceive the line conductor. The test circuit is electrically connectedto the printed-circuit board coil. The test circuit is configured todetermine an arc fault condition based on a signal of theprinted-circuit board coil

Other aspects of the application will become apparent by considerationof the detailed description and accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective cutaway view of a circuit interrupting deviceaccording to some embodiments.

FIGS. 2A and 2B are perspective views of a core assembly of the circuitinterrupting device of FIG. 1 according to some embodiments

FIG. 3 is a perspective view of a coil of the circuit interruptingdevice of FIG. 1 according to some embodiments.

FIG. 4 is a block diagram of a control system of the circuitinterrupting device of FIG. 1 according to some embodiments.

FIG. 5 is a block diagram of an arc fault detector of the control systemof FIG. 4 according to some embodiments.

FIG. 6 is a perspective view of a printed-circuit board of a circuitinterrupting device according to some embodiments.

FIG. 7 is a perspective view of a printed-circuit board of a circuitinterrupting device according to some embodiments.

DETAILED DESCRIPTION

Before any embodiments of the application are explained in detail, it isto be understood that the application is not limited in its applicationto the details of construction and the arrangement of components setforth in the following description or illustrated in the followingdrawings. The application is capable of other embodiments and of beingpracticed or of being carried out in various ways.

FIG. 1 is a perspective cutaway view of a circuit interrupting device100 according to some embodiments. The circuit interrupting device 100includes a housing 105 having a front cover 110 and a rear cover 115.The housing 105 may be formed of plastic, or a similar material.

The front cover 110 may include a duplex outlet face 120 with a phaseopening 125, a neutral opening 130, and a ground opening 135. The face120 may further include an opening 140 accommodating a RESET button 145.Although not illustrated, in some embodiments, the face 120 may includeadditional openings to accommodate additional buttons (for example, aTEST button), as well as additional openings to accommodate variousindicators (for example, light-emitting diodes (LEDs), buzzers, etc.).The rear cover 115 is secured to the front cover 110 and may include oneor more terminal screws 150. In some embodiments, the terminal screws150 include a line terminal screw, a neutral terminal screw, and/or aground terminal screw. Contained within the front and rear covers 110,115 is a manifold 155. Manifold 155 provides support for a yoke/bridgeassembly 165 configured to secure the device 100 to an electrical box.

FIGS. 2A and 2B illustrate perspective views of a core assembly 200according to some embodiments. The core assembly 200 is configured tosupport a printed circuit board 205 that supports most of the workingcomponents of the device 100, including the control system 400illustrated in FIG. 4. The core assembly 200 further supports a lineconductor 210 and a neutral conductor 215. The line and neutralconductors 210, 215 are respectively electrically connected to the lineterminal and neutral terminal, and are configured to supply electricalpower to the device 100.

The core assembly 200 may further support a first coil 220 and a secondcoil 225. As illustrated, the first and second coils 220, 225 mayrespectively include first and second apertures 230, 235. In someembodiments, the first aperture 230 is configured to receive the lineconductor 210, while the second aperture 235 is configured to receivethe neutral conductor 215. In some embodiments, the first and secondcoils 220, 225 may respectively be embedded into first and secondprinted circuit boards 240, 245. In other embodiments, the first andsecond coils 220, 225 may be embedded into a single printed circuitboard. In some embodiments, the first coil 220 and the second coil 225are printed circuit board coils.

The core assembly 200 may additionally support a third coil 250 having athird aperture 255. In some embodiments, the third aperture 255 isconfigured to receive both the line conductor 210 and the neutralconductor 215.

FIG. 3 illustrates one embodiment of the first coil 220 with the printedcircuit board removed for illustrative purposes. As illustrated, thefirst coil 220 may be a Rogowski coil having an input 305 and an output310. As illustrated, the coil 220 further includes an upper portion 315,a lower portion 320, an inner portion 325, an outer portion 330, aplurality of helical conductors 335, and a plurality of nodes 340,connecting the input 305 to the output 310. As illustrated, the helicalconductors 335, along with the nodes 340, form the coil 220. Forexample, the plurality of conductors 335 form a portion of the coil 220between the inner portion 325 and the outer portion 330, while theplurality of nodes 340 form the coil 220 between the upper portion 315and the lower portion 320.

In some embodiments, the second coil 225 is also Rogowski coil, similarto coil 220. Although not illustrated, in some embodiments the thirdcoil 250 may also be a Rogowski coil embedded on a printed circuit board(for example a third printed circuit board or a single printed circuitboard including the first, second, and third coils 220, 225, 250. Insome embodiments, coils 220, 225, and/or 250 are printed-circuit boardcoils that do not have a Rogowski coil configuration.

FIG. 4 is a block diagram of a control system, or testing circuit, 400of the device 100 according to some embodiments. The control system 400includes a controller, or microcontroller, 405 electrically connected tothe first coil 220, the second coil 225, and the third coil 250. Thecontroller 405 is configured to detect one or more fault conditions, andplace the device 100 into a tripped state when the one or more faultconditions are detected. In some embodiments, the controller 405 is awell-known integrated circuit device having an electronic processor anda memory, such as but not limited to a 4145 device.

The controller 405 may include a ground fault detection unit 410, aresonator 415, an arc fault detection unit 420, and a time-domaincorrelator and analyzer 425. In some embodiments, the ground faultdetection unit 410, the resonator 415, the arc fault detection unit 420,and/or the time-domain correlator and analyzer 425 are implemented inwhole or in part in software. In some embodiments, there is no separatemodule, but rather the ground fault detection unit 410, the resonator415, the arc fault detection unit 420, and/or the time-domain correlatorand analyzer 425 are implemented using software stored in the memory ofthe controller 405 and executed by the processor of the controller 405.

The ground fault detection unit 410 is configured to analyze electricsignals from the third coil 250. The ground fault detection unit 410 isconfigured to detect a ground fault (for example, a real ground fault, asimulated ground fault, a self-test ground fault, and/or a real orsimulated grounded neutral fault based on the electric signals from thethird coil 250. The resonator 415 is configured to analyze a frequencyof the power supplied to the device 100.

The arc fault detection unit 420 is configured to analyze electricsignal from the first coil 220 or from the first coil 220 and secondcoil 225. The arc fault detection unit 420 is configured to detect anarc fault (for example, a real arc fault, a simulated arc fault, and/ora self-test arc fault) based on the electric signals from the first coil220 or from the first coil 220 and second coil 225. The time-domaincorrelator and analyzer 425 is configured to perform a time-domaintransformation and/or analysis on the electric signals from the firstcoil 220 or from the first coil 220 and second coil 225. The transformedelectric signals are then analyzed by the arc fault detection unit 420to detect an arc fault. In some embodiments a discrete Fourier transform(DFT) is performed on the electric signal and then analyzed to furtherdetermine an arc fault.

FIG. 5 is a block diagram of the arc fault detection unit 420 accordingto some embodiments. In such an embodiment, the arc fault detection unit420 includes a bandpass filter 505, an integrator 510, and a gain stage,or scaling module, 515. The electric signals from the first coil 220 orfrom the first coil 220 and second coil 225 are filtered by the bandpassfilter 505 and then integrated by integrator 510 in order to determine avoltage of the electric signal(s). In some embodiments, the voltage isproportional to a current flowing through the first coil 220 and/or thesecond coil 225. In some embodiments, the bandpass filter 505 is a 3-dBpass-band filter between 1-Hz and 8-kHz, which attenuates unnecessarylow and high frequency content that might otherwise saturate theintegrator 510. Once integrated, the gain stage 515 scales the signal toa full-scale input voltage of an analog-to-digital (A/D) converter,which will sample the signal for subsequent digital post-processing. Forexample, a 30-Arms line-current may be scaled to a full-scale voltage ofapproximately 3.0 Vdc by the A/D converter. In some embodiments, the A/Dconverter is embedded within the controller 405.

As illustrated in FIG. 5, in some embodiments, the interrupter 100 mayfurther include coils 520, 525. Coil 520 may be electrically connectedto coil 220 in a series-type configuration, while coil 525 may beelectrically connected to coil 225 in a series-type configuration. Coils520, 220 and coils 525, 225, when respectively electrically connected ina series-type configuration, may produce respective measured signalsthat are multiplied by a n number of coils connected in the series-typeconfiguration. Such an embodiment may allow for a greater measuredsignal.

FIG. 6 illustrates a printed-circuit board 600 according to someembodiments. Printed-circuit board 600 may be part of, or included in,circuit interrupting device 100. The printed-circuit board 600 mayinclude one or more printed-circuit board coils 605, one or moreelectronic components 610, and one or more electrical pins 615.Printed-circuit board coils 605 may be substantially similar to coils220, 225, and/or 250. The one or more electrical components 610 mayinclude one or more components discussed above with respect to FIGS. 4and 5. For example, the one or more electrical components 610 may be, ormay include, a programmable microcontroller. The one or more electricalpins 615 may be configured to electrically and/or communicativelyconnect the printed-circuit board 600 to other components of the circuitinterrupting device 100.

In the illustrated embodiment, printed-circuit board 600 furtherincludes one or more slots, or apertures, 620. The slots 620 may beconfigured to receive the line conductor 210 and/or neutral conductor215.

FIG. 7 illustrates a printed-circuit board 700 according to otherembodiments. Printed-circuit board 700 may be part of, or included in,circuit interrupting device 100. The printed-circuit board 700 mayinclude one or more coils 705 and one or more slots, or apertures, 710.In the illustrated embodiment, the one or more coils 705 are wire-woundcoils. The slots 710 may be configured to receive the line conductor 210and/or neutral conductor 215.

In operation, the coils (for example, coils 220, 225, 250, 605, and/or705) may be used to sense and/or monitor a current. An arc condition maythen be determined based on the current. In some embodiment, an arccondition may be determined by determining if a correlation condition, avolatility condition, and/or an impulse condition exists. Additionally,in some embodiments, an in-rush condition may be detected via the coils.

Thus, the application provides, among other things, a circuitinterrupting device having a printed circuit board coil. Variousfeatures and advantages of the application are set forth in thefollowing claims. For example, one advantage of the application includesan increase in within an electrical receptacle due to the reducedfootprint of using one or more printed circuit board coils.

What is claimed is:
 1. A circuit interrupter comprising: a lineconductor; a neutral conductor; a printed-circuit board coil embedded ona printed circuit board, the printed circuit board including a slotthrough the printed-circuit board coil, the slot configured to receivethe line conductor; a second printed-circuit board coil embedded on theprinted circuit board, the printed circuit board further including asecond slot through the second printed-circuit board coil, the secondslot configured to receive the neutral conductor; and a test circuitelectrically connected to the printed-circuit board coils, the testcircuit configured to determine an are fault condition based on a signalof the printed-circuit board coil.
 2. The circuit interrupter of claim1, wherein the test circuit is configured to determine the are faultcondition based on the signal of the first printed-circuit board coiland a second signal of the second printed-circuit board coil.
 3. Thecircuit interrupter of claim 1, wherein the test circuit determines thearc fault condition by: receiving the signal, performing a time-domainanalysis on the signal, and determining the are fault condition based onthe time-domain analysis.
 4. The circuit interrupter of claim 1, whereinthe test circuit includes a bandpass filter configured to filter thesignal.
 5. The circuit interrupter of claim 1, wherein the test circuitincludes an integrator configured to determine a signal voltageproportional to a current of the signal.
 6. The circuit interrupter ofclaim 1, wherein the test circuit includes a gain stage configured toscale the signal.
 7. The circuit interrupter of claim 1, furthercomprising a second printed-circuit board coil electrically connected tothe test circuit, the second printed-circuit board coil having a secondaperture configured to receive the line conductor and the neutralconductor.
 8. The circuit interrupter of claim 1, wherein the testcircuit is further configured to: determine a ground fault based on oneor more signals of the printed-circuit board coil.
 9. The circuitinterrupter of claim 1, further comprising a second printed-circuitboard coil having a second aperture configured to receive the neutralconductor, wherein the printed-circuit board coil and the secondprinted-circuit board coil are embedded on a printed circuit board. 10.The circuit interrupter of claim 1, wherein the printed-circuit boardcoil is a Rogowski coil.
 11. The circuit interrupter of claim 1, whereinthe printed-circuit board coil and the test circuit are located on theprinted circuit board.